4.3 mm holes, 20 mm deep

[Chaz]

So your going to be doing some tapping?

I would just spot drill (good them osborn/europa), then open them up as normal i.e jobber/twist drill bit, I've been using these Heller HSS German made bits pretty much exclusively recently without fail.

They do HSS-R and HSS-G versions, R is for non alloyed steels and G is aimed at alloyed, the G have a 135 degree split point for optimum centering and dimensional accuracy.

You can find them all over eBay if you search, I've even got their 15 and 20mm "black smith" type to open up clearance holes for my leadscrews...they worked sweet as a nut!

I wouldn't go anything less than the 4.3 you need, use the 4.3 for the 5.3 as well so you've got a nice pilot hole you can then open up, use plenty of cutting oil and take your time, dont forget to give the holes a small chamfer to help the tap locate :)

Thanks.

Phantom Drills came back and offered this:-

Phantom drill 11.770

They are cheaper than carbide, around £5 each. This was based on my requirement to do 'high speed' drilling due to limited low speed torque with the Chinese spindle.

This wont be tapped, its a through hole for a bolt.

[Lee Roberts]

This wont be tapped, its a through hole for a bolt.

Ok so the .3 is putting you in the middle of standard and close fit, what I've linked to should give you what you need for a through/clearance hole of fairly good accuracy surely?

[Chaz]

Ok so the .3 is putting you in the middle of standard and close fit, what I've linked to should give you what you need for a through/clearance hole of fairly good accuracy surely?

Yep, exactly. Ill order those drill bits, seems good value for money and keep for future if I ever need to do similar again.

[Lee Roberts]

Yep, exactly. Ill order those drill bits, seems good value for money and keep for future if I ever need to do similar again.

Cool, if you look I think you can just buy 1 bit at a time for 99p all in or something from another seller, saves buying a box of 10.

I'll confirm what I've got if you want and send you?

[EddyCurrent]

Number Drill set; http://www.ebay.co.uk/itm/RDGTOOLS-6...EAAOSwx~JWFOOB

[Chaz]

Number Drill set; http://www.ebay.co.uk/itm/RDGTOOLS-6...EAAOSwx~JWFOOB

Thanks.

[routercnc]

Are these clearance holes for 4 and 5mm bolts?
If so you can just drill them 4 and 5 mm because the bolts are slightly under size.
I often drill 0.5mm larger just to get me some assembly allowance but that is just a convenience

I think one of your worries is whether the Chinese spindle will drill holes in this size due to limited torque. Well because the drills are small you can spin them quickly so there are no issues there and I regularly mill 3 mm holes using a twist drill to 15mm depth.
You need to watch the flutes blocking after about 10mm so need to do small pecks and wipe the bit with an oiled brush each time it comes out of the hole between pecks. If it welds in the hole it will snap off and ruin your day.

Are these shoulder bolts? If so you can ream them after drilling to register on the shoulder.

[Chaz]

Cool, if you look I think you can just buy 1 bit at a time for 99p all in or something from another seller, saves buying a box of 10.

I'll confirm what I've got if you want and send you?

Sure, thanks, happy to pay.

[cncmachineokk]

I have 4mm endmill length 22mm.

[Chaz]

I have 4mm endmill length 22mm.

Where did you get these from?